1. Field of the Invention
The present invention relates to a method of manufacturing an organic electroluminescence (EL) element.
2. Description of the Related Art
The structures of organic EL elements can be classified into a normal layered structure and inverse layered structure. In the normal layered structure, an anode, an organic layer including an emitting layer, and a cathode are stacked in this order on a substrate. In the inverse layered structure, these components are stacked in the reverse order. In these organic EL elements, a transparent conductive oxide such as ITO (indium tin oxide) is normally used as the material of the anode, and a metal or alloy is normally used as the material of the cathode.
The structures of the organic EL elements can also be classified into a bottom emission structure and top emission structure. In the bottom emission structure, light emitted by the emitting layer is extracted from the substrate side. In the top emission structure, light emitted by the emitting layer is extracted from the opposite side. Presently, many organic EL elements use the normal layered structure regardless of whether they have the bottom emission structure or top emission structure.
Jpn. Pat. Appln. KOKAI Publication No. 4-14794 describes aging which is performed to stabilize the emission of an organic EL element. In this aging, a forward voltage, a reverse voltage, or a voltage having a waveform obtained by combining these voltages is applied to an organic EL element.